每次我在python中循环时如何创建节点

Question

I like to create a nodes every time when i go through a loop.But presently only the last value of the loop will be used. How can i achieve this using python. following is my example.

My xml :-

<person>
<user name="david" password="super"></user>
<user name="alen" password="boss"></user>
<user name="windeesal" password="sp"></user>
</person>

The python code:

import xml.etree.ElementTree as ET

doc = ET.parse("users.xml")
root = doc.getroot() #Returns the root element for this tree.
root.keys()          #Returns the elements attribute names as a list. The names are returned in an arbitrary order
for child in root:
    name = child.attrib['name']
    password = child.attrib['password']

root = ET.Element("person")
user = ET.SubElement(root, "user")
user.set("username",username)
user.set("password",password)

tree = ET.ElementTree(root)
myxml = tree.write("new.xml")

print myxml 

Out put of the code contain only last value of loop :(

<person>
<user password="sp" username="windeesal" />
</person>

how to create the nodes every time i go through the loop then join the results and write them to the file .? am really a beginner please give me a detail explanation. Thank you very much .

Answer 1

Try next one. Your understanding of python seems to be very basic so I am not sure what to write about problem.

Please ask if you need explanation! :)

import xml.etree.ElementTree as ET

doc    = ET.parse("users.xml")
root = doc.getroot() #Returns the root element for this tree.
root_new  = ET.Element("person") 
for child in root:
    name                = child.attrib['name']
    password             = child.attrib['password']

    user  = ET.SubElement(root_new, "user") # create subelement in cycle! 
    user.set("username",name)               # username variable is not declared
    user.set("password",password)

tree = ET.ElementTree(root_new)
tree.write("new.xml")

import sys
tree.write(sys.stdout)

Answer 2

The trick to "creating nodes every time I go through a loop" is to create the node inside the loop. You want:

for child in root:
    name     = child.attrib['name']
    password = child.attrib['password']

    user = ET.SubElement(root_new, "user")
    user.set("username", name)
    user.set("password", password)

Python is whitespace-sensitive. If you don't indent those bottom three lines, they're not part of the loop.

Answer 3

You are overwriting the tree read in root. Append to what youve read

import xml.etree.ElementTree as ET

doc    = ET.parse("users.xml")
root = doc.getroot() #Returns the root element for this tree.
root.keys()          #Returns the elements attribute names as a list. The names are returned in an arbitrary order
for child in root:
    name                = child.attrib['name']
    password             = child.attrib['password']

user  = ET.SubElement(root, "user")
user.set("username",'test')
user.set("password",'me')

tree = ET.ElementTree(root)
tree.write("new.xml")

Also check new.xml for result. tree.write returns None apparently